Anatomical variations of the superior thyroid artery: insights from a comprehensive digital subtraction angiography study

In neck anatomy, the superior thyroid artery (STA) is typically considered the first branch of the external carotid artery (ECA). However, variations in the origin of the STA can pose challenges during surgical interventions. In this study, using digital subtraction angiography, we reached the largest patient sample in the literature (186 patients, 372 heminecks). Our findings indicate that 54.6% of the STAs originate from the ECA, 24.2% from the carotid bifurcation (CCAB), and 21.2% from the common carotid artery (CCA). The high proportion of non-ECA origins (45.4%) challenges the traditional assumption that the STA is the first branch of the ECA. The STA originates from the ECA at nearly equal rates on both sides of the neck (right 54.8%, left 54.3%). The origin rate from the CCAB is higher on the right (right 26.3%, left 22), while the CCA origin rate is higher on the left (right 19.4%, left 23.1) (p=0.008). ECA origins are more frequent in males at 60.5%, CCAB origins in females at 27.1%, and CCA origins in females at 27.8% (p=0.009). In female patients, the ECA origin on the left side is more prevalent at 52.8%, while the CCAB and CCA origins on the right side are 29.2% and 33.3% respectively (p=0.01). Additionally, we detected STA origin symmetry in 48.9% of patients (p=0.003). In female patients, 52.8% had symmetric STA origins (p=0.037). The observed diversity in STA origins underscores the need for a comprehensive and up-to-date review of critical anatomical knowledge for surgical interventions.